Needle-Free Injection Devices Face Obstacles

BETHESDA, MD. -- Needle-free jet injection devices can and should play
a major role in solving the problems of needle-stick injuries and needlephobia
in the United States, Dr. Bruce G. Weniger said at a meeting on needle-free
injection sponsored by the Centers for Disease Control and Prevention.

Yet the needle-free jet injector industry is struggling to overcome
significant obstacles in this country and abroad before these devices become
widely accepted and used for administering drugs and especially for administering
vaccines, said Dr. Weniger, assistant chief for vaccine development at
the Centers for Disease Control and Prevention's National Immunization
Program in Atlanta.

Most needle-free jet injectors use metal springs, compressed air,
or CO2 gas to power the injection. The
device's nozzle is held against the patient's skin at the injection site,
and once activated, the device injects a fine stream of the vaccine or
drug at a high pressure, penetrating into the skin.

The most common orifice size is 0.127 mm, whereas that of a 25-gauge
needle is 1 mm, he noted.

Around the world, needle-free jet injectors have a small but established
market among diabetic patients who do not share them with others.

In this country, about a dozen needle-free jet injectors have
been licensed by the Food and Drug Administration and are on the market.

A few of these devices are being used in physicians' offices and clinics
across the country.

One of the more popular needle-free jet injection devices used
to deliver vaccines, according to Dr. Weniger, is the Biojector 2000.

This particular device is being used by 116 office-based physicians
in the United States, according to a spokesperson for Bioject Inc., the
Portland, Ore.-based manufacturer.

Currently, each manufacturer makes its own type of cartridge that
holds the vaccine and is attached to the device before injection.

None of these cartridges are interchangeable, and that is a major limitation
to their widespread use in physicians' offices in this country, said Dr.
Weniger, who is promoting standard cartridge interfaces to solve the problem.

Third World countries would benefit greatly from needle-free injection
technology, since many underdeveloped countries have a high rate of reusing
disposable needles and have tremendous problems with safely disposing of
them, Dr. Weniger said at the meeting, which was also sponsored by the
World Health Organization and the Association of Needle-Free Injection
Manufacturers.

But a key barrier is that current needle-free cartridges cost
several times what developing countries now pay for conventional syringes
and needles, the physician added.

However, Donatus Ekwueme, Ph.D., a CDC economist, presented an
analysis showing that the hidden costs of iatrogenic disease from unsafe
reuse of syringes in many African settings greatly exceeded the extra costs
for needle-free injection devices.

Needle-free jet injectors can be categorized as either high-workload
devices, which can inject more than 150 people per health care worker per
hour and are designed for mass immunization campaigns, or low-workload
devices, which can inject about 30 people per health care worker per hour
and are intended for use in physicians' offices.

One major concern associated with the use of older devices that use
the same metal nozzle for consecutive vaccinees is the potential for the
transmission of infectious diseases from one patient to another, Dr. Weniger
said.

The World Health Organization has issued a moratorium on the use
of such high-workload devices, except in cases of an emergency, because
of the fear of disease transmission in mass immunization campaigns.

In 1986, a high-workload jet injector was linked to the transmission
of hepatitis B in at least 31 patients who were receiving injections of
human chorionic gonadotropin via the device at a weight reduction clinic
in Long Beach, Calif.

Experts are unsure of the exact transmission mechanism. One theory is
that minute quantities of blood or tissue fluid are transferred to the
nozzle of the device as it injects a product, and these are then injected
along with the product to the next patient.

Manufacturers of newer devices have solved this problem by using
disposable, single-use-only cartridges/nozzles in order to prevent transmission
of infectious diseases.

The immune responses induced by needle-free injection devices
tend to be equivalent to and often better than those by needle and syringe,
Dr. Weniger said.

But immediate local reactions of erythema and hematoma and delayed
soreness tend to occur more frequently with jet injectors than with needles
and syringes. Injection sites from needle-free jet injections are also
more likely to bleed than are injection sites from needles and syringes.

These devices were initially touted as being pain free or at least
as causing less pain than needles and syringes. But recent studies have
indicated that pain may be equivalent to or even greater than that associated
with needles, Dr. Weniger said.